In the party’s eyes, Guingouin had become “an enemy of the worst kind”; he had dared to question the apparatus of Comintern and the hierarchy of the party in France. Having been excluded from the party, and denied the protection that this offered, old grievances were quick to reappear. Central among the character assassins was the head of the Socialist Federation and Deputy of the Haute-Vienne, Jean Le Bail. Educated on the likes of Jean-Paul Sartre, Raymond Aron and Paul Nizan at university, Le Bail exhibited only contempt for the Resistance and its former members. Writing in the Populaire du Centre, Le Bail named the Limousin as The “Land of Terror” and Guingouin as the “Massacre Colonel”.

Curiously, three months after Guingouin’s exclusion from the party, the police force re-opened their investigations into several murders which, over time, had become known as the "Massacres of Chamberet".

In July 1944, in the hamlet of Estivallerie, the family Dutheil: father, mother, and nineteen year old son were all assassinated, Mme Dutheil was suspected of black marketeering. In the following days, and very close to Estivallerie, six Council officers, in a town whose former socialist mayor, Rene Buisson, had been “removed” by the Vichy, were allegedly taken and assassinated on the orders of Captain Charlot, a resistance fighter from Creuse. Several nights later the body of the supposed Captain Charlot, riddled with bullets, was deposited in the main street of the town. A placard also appeared on the door of the town hall denouncing Charlot as an agent of the Milice, who had infiltrated the Maquis. Finally, and over a year later, on November 27, 1945, two farmers from Domps, Haute-Vienne, were going to market to buy a cow. On the way they were murdered in a wood and the 30,000 Francs they were carrying was stolen.

These crimes of the late war period became, for some unknown reason, amalgamated into a single case, with Guingouin as the chief suspect, even though a number of people were serving jail sentences for these crimes having been fully investigated, charged and sentenced.

Within months, and following an investigation by police officers of the former Vichy, who had been reinstated into the police service following the end of the war, Guingouin faced magistrates who had, during the war, given an oath to Marshal Pétain.. As a result, on December 24, 1953, Guingouin was sentenced and imprisoned at Brive, a prison well known for its extremely harsh conditions.

On February 23, 1954 an attempt was made on Guingouin’s life, as fumes were passed through his cell. But given that this was classed as a suicide attempt, Guingouin was classified as mentally unstable and was transferred to a psychiatric hospital in Toulouse.